Gunshot residue (GSR) was deposited on porcine tissue with hand loaded non-jacketed (NJ) and full-jacketed (FJ) ammunition at two different firing distances. Fresh tissue samples, as well as samples collected throughout decomposition were microwave digested in nitric acid and analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) to determine the elemental composition of the GSR. Element concentrations for lead (Pb), antimony (Sb), barium (Ba), copper (Cu), iron (Fe), and zinc (Zn) were statistically compared in order to investigate differentiation of bullet type and firing distance based on chemical concentrations in the GSR. Control (unshot) samples were collected in order to assess for environmental contaminants. Results of this study demonstrated that ICP-OES was adequate to detect the characteristic elements of GSR in fresh tissue, but was not sensitive enough to detect all elements throughout decomposition. Lead and Sb were significantly greater in NJ samples. Barium was useful in differentiating firing distance for both bullet types, while Cu was used to differentiate firing distance in FJ ammunition only. Analysis using ICP-MS, which has detection limits up to three orders of magnitude lower compared to ICP-OES, demonstrated the persistence of Pb, Sb, and Ba on porcine tissue throughout decomposition at a firing distance of 5 cm for both NJ and FJ ammunition.
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